Neonatal brachial plexus palsy (NBBP) is a stretch injury to the brachial plexus (BP) during the birth process, resulting in varying degree of paralysis. No data exists on the biomechanical and functional responses and associated structural damage of the complex BP when subjected to stretch. Detailed knowledge of these properties are required to fully characterize the mechanism of injury that will allow clinicians to develop strategies that minimize the occurrence of NBPP and also guide treatment strategies. The aims of this study are to determine the biomechanical and physiological injury thresholds and the resulting structural changes during stretch injuries to the neonatal BP. The study further expands to develop a more human-like computational model, which can be used to advance the science of obstetrical care through training and education. All proposed aims of this study would engage several undergraduates thereby enhancing the research program at Widener University. Proposed Specific Aim 1 will provide a detailed understanding of the biomechanical properties of the neonatal BP complex through in vivo tensile testing of the neonatal BP in an experimentally powerful piglet animal model. Specific Aim 2 will identify the functional injury thresholds of the neonatal BP. By subjecting various segments of the BP to known strains, we will determine the threshold for both spontaneous recovery as well as permanent functional damage in the BP complex after stretch injuries. No such data is available in the literature, which limits the prognosis of the injury and treatment selection. Specific Aim 3 will identify the histological changes in the BP post stretch injury, including changes in the nerve fibers, such as increased spacing or torn fibers, myelin changes, extent of blood vessel rupture, and impaired axoplasmic transport. Histological findings will greatly enhance the understanding of the injury mechanism. Specific Aim 4 will use the data from Aims 1 & 2 to improve the human like behavior of an existing computational model that will then be used to identify the range of injury severities that occurs to the BP during current delivery maneuvers. This model can also be used to investigate new clinically translational obstetrical maneuvers that can minimize BP stretch. In summary, this study will be the first to provide the required scientific knowledge to better understand the mechanism of NBPP, identify optimal treatment options and further advance obstetrical care by providing a model that will not only help train the care providers to minimize the occurrence of NBPP but also develop new delivery maneuvers that can prevent NBPP.